Pharmacology L5 Flashcards

1
Q

How do drugs work

A
  • drugs must exert some
    chemical influence on one or more constituents of cells
  • there must be non-uniform distribution of drugs within the body
  • they interact with specific binding sites to modify the physiological/ biochemical state of cells, tissues and organs
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2
Q

Major targets of drug action are

A

-Hormones
-Ion channels
-Carriers
-Enzymes
- Membrane receptors
- Nuclear receptors
- DNA

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3
Q

What are the levels of drug action

A

MOLECULAR
CELLULAR
TISSUE
SYSTEM

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4
Q

Molecular level of drug action

A

Biomolecules as immediate targets of drugs

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5
Q

Cellular level of drug action

A

Biochemical constituents in the process of transduction

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6
Q

Tissue level of drug action

A

Alters organ function

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7
Q

System level of drug action

A

Alters system function

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8
Q

How do drug-receptor interactions occur

A

through reversible non-covalent bonds

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9
Q

Drug-receptor interactions

A
  • Highly stable ion-ion electrostatic attraction
  • Partial charge dipole-ion electrostatic
  • Partial charge dipole-dipole electrostatic
  • Low strength van de Waals’ electrostatic attraction between apolar groups
  • Hydrophobic interactions of apolar molecules in an aqueous environment
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10
Q

How do most drugs exert their properties

A

by binding protein domains

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11
Q

Protein targets for drug binding

A
  • Receptors
  • Ion channels
  • Carrier
  • Enzymes
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12
Q

Specificity of drug action

A

reciprocal or dose-dependent

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13
Q

Reciprocal drug action

A

Some drugs bind only to certain molecular and cellular targets. Certain molecular and cellular targets recognize only certain classes of drugs.

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14
Q

Dose-dependent specificity of drug action

A

Increasing the dose of drug will affect molecular targets other than the principal pharmacological one, causing toxic side-effects.

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15
Q

What is an Agonist

A

Drug that binds and activates its respective receptor.

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16
Q

What is affinity

A

Tendency of a drug to bind to a receptor.
Receptor occupation by drug is governed by affinity.

17
Q

What is efficacy

A

Tendency of a drug, once bound, to activate the receptor. Receptor activation by bound drug is governed by efficacy

18
Q

What is an antagonist

A

Drug that binds to receptor without triggering activation, thus preventing binding of agonist/physiological ligand.

19
Q

What is a Maximal pharmacological response

A

The maximal response on a particular receptor differs between chemically
related agonists

20
Q

What is a maximal response

A

The largest response that a tissue can give
if triggered by a specific substance at high concentration.

21
Q

Why is the therapeutic dose of a drug sometimes lower then its maximal response dose

A

Due to toxic side effects

22
Q

What is a log-dose response used for

A

to quantify the relationship between biological responses and agonist concentration

23
Q

What is a full agonist

A

A drug that can produce a maximal response

24
Q

What is a partial agonist

A

A drug that can only trigger a sub-maximal response.

25
Q

What happens if a tissue contains a receptor reserve due to poor intrinsic efficacy

A

allows partial agonist to act as a full agonist.

26
Q

What is a receptor reserve

A

agonist only needs to activate a smaller number of receptors than the total number available to produce a maximal response

27
Q

what is intrinsic efficacy

A

the ability of a drug- receptor complex to produce a maximal response

28
Q

What is a competitive agonist

A

Substance that has no intrinsic efficacy and binds reversibly with receptor. It dilutes the receptor concentration. Importantly, an increase of agonist dose can return tissue response to normal. (uses up receptor that agonist can use, can be removed)

29
Q

What is an irreversible agonist

A

Causes blocking of a receptor that cannot be reversed by increasing the agonist concentration. high concentrations of agonist leads to depression of the maximum response.

30
Q

Function of agonistic versus antagonistic blocking action
in Nicotinic acetylcholine receptor (nAChR)

A

Skeletal muscles are relaxed during surgical procedures by using neuromuscular drugs (agonists/ antagonists) to cause clinical paralysis of voluntary muscles.

31
Q

What is the competitive antagonist that can function in nAChR

A

Tubocurarine

32
Q

How does Tubocurarine function as an antagonist

A

It competes with the native ligand neurotransmitter acetylcholine for the receptor. However, it does not cause a biological response

33
Q

What is the agonist that functions in nAChR

A

Suxamethonium

34
Q

How does Suxamethonium work

A

It depolarizes the neuromuscular junction but does not dissociate rapidly from the nAChR complex causing a neuromuscular block

35
Q

Molecular approaches used in the structural analysis of pharmacologically important protein receptors

A

¤ Protein purification and characterization
¤ Affinity purification and characterization
¤ Protein/peptide N-terminal sequence analysis
¤ Mass spectrometric analysis of protein subunits
¤ Cloning and sequencing of cDNA
¤ High-resolution x-ray crystallography
¤ High-resolution cryo-electron microscopy
¤ Differential co-immuno precipitation methodology
¤ Chemical cross-linking analysis
¤ Native two-dimensional gel electrophoresis
¤ Gel filtration analysis